White balance adjustment device

ABSTRACT

A white balance adjustment device adapted to be used in contexts where a photographic subject is illuminated with fluorescent lighting. The white balance adjustment device includes an imaging device for forming an image of a photographic subject and for outputting signals representing the image. An adjustment mode selection device is included for selecting a white balance adjustment mode according to the kind of light source used to illuminate the photographic subject. A measurement unit is used to measure color aspects of the light source used to illuminate the photographic subject. White balance adjustment circuitry is included to adjust the white balance of the output of the imaging device in accordance with the adjustment mode selected by the adjustment mode selection device and in accordance with the measured color aspects of the light source used to illuminate the subject. A method of performing white balance adjustment includes the steps of imaging a subject to produce a video signal representing an image of the subject, color separating the video signal into its primary light color components, measuring the color attributes of light used to illuminate the subject to produce a color measurement value, matching the color measurement value with a predetermined parameter to produce a processing parameter which corresponds to the type of light used to illuminate the subject, and performing white balance adjustment of the video signal using the processing parameter.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to white balance adjustment devicesparticularly suitable for television cameras, video cameras, electronicstill cameras, and the like.

2. Description of the Related Art

White balance adjustment devices of cameras are well known. FIG. 1, forexample, shows a well-known white balance adjustment device which isused in a color camera. Imaging unit 403 is an element which convertslight into electrical signals. The imaging unit is typically acharge-coupled (CCD) device, a metal oxide semiconductor (MOS) device,or other form of solid-state imaging device. A circuit samples theoutput signals from imaging unit 403 at a predetermined rate. Inparticular, light rays are received from a photographic subject (notshown) via the optical member 401 and stop member 402. Respective R(red), G (green), and B (blue) signals are output from the imaging unit403. The G output signals are transmitted directly to a signal processor405; the R output and the B output are transmitted to the signalprocessor 405 via respective white balance variable amplifier circuits404R and 404B controlled by means of a control unit 410 according to theoutput of a color measurement unit 430. Typically, as the light sourcevaries, the levels of the R and B signals are adjusted, usually so thatthere is a natural color balance, based on the G signal level. Thesignal processor 405 performs the adjustment of gain, set-up level,gamma and knee, etc., and transmits image signals to a recording unit406.

The prior art white balance adjustments which are made by means ofvariable amplifier circuits 404R and 404B will next be described. Light,received by the color measurement unit 430 from the camera surroundings,is passed through a diffusing plate 431 to a R red light receivingelement 432R, to a G green light receiving element 432G, and to a B bluelight receiving element 432B, and from the respective light receivingelements there are output signal currents corresponding to the redcomponent (Rb), green component (Gb) and blue component (Bb) of theincident light. After these signal currents have been converted intologRb, logGb and logBb signals by respective logarithmic compression bya logarithmic compression circuit 433, log (Rb/Gb) and log (Bb/Gb) arecalculated in subtraction circuits 434 and 435, and are furthermoreconverted into Rb/Gb, Bb/Gb by antilog conversion in the expansioncircuit 436. After conversion into voltage signals by thecurrent/voltage converter circuit 437, they are converted into digitalsignals by the A/D converter 409 and are output to control unit 410.

In the case that the auto white balance mode is selected by means of aswitch 421, the gain of the variable amplifier circuits 404R and 404Bcorresponding to the measured color results Rb/Gb, Bb/Gb is "looked up"or retrieved from a previously prepared control table 408A for autowhite balance use, and is set in the respective amplifier circuits 404Rand 404B.

If the auto white balance mode is not selected via switch 421 and,alternatively, the white balance mode is selected to be in a "fineweather," "cloudy," "fluorescent lamp," or "tungsten lamp" mode viacorresponding switches 422-425 (i.e., a manual white balance mode), thegain corresponding to the selected light source of the manual mode islooked up from a previously prepared control table 408M for manual whimbalance use, and is set in the respective amplifier circuits 404R and404B.

While prior art white balance adjustment devices of the type discussedabove have been in use for some time, in recent years various new lightsources have emerged including, but not limited to, color electricbulbs, white color emitters, daylight white color emitters, daylightcolor emitters, and various fluorescent lighting arrangements and lamps.Such new lighting and illumination sources present problems for priorart white balance adjustment devices. For example, photographic picturecoloration is often too red or too blue, depending on the kind offluorescent lamp which is used as an illumination source. This problemresults with prior art white balance adjustment devices since suchdevices use the same control values and parameters for white balanceadjustment regardless of the fluorescent lighting source actually beingused to illuminate a subject.

In order to solve the aforementioned problems, selection switches werearranged for electric bulb color, white color, daylight white color,daylight color and the like in the fluorescent lamp manual mode, and thephotographer, selecting according to the kind of fluorescent lamp, forexample, could make an adjustment for the optimum color balance.However, it is difficult for photographers to determine exactly the kindof fluorescent lamp being used by mere visual inspection during use of acamera, for example.

The present invention solves the aforementioned and numerous otherproblems associated with white balance adjustment in photographic/videosettings.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to solve theabove-mentioned and other problems associated with conventional whitebalance adjustment devices.

It is therefore another object of the present invention to provide awhite balance adjustment device which provides high accuracy whitebalancing in the contexts of video and photographic processing.

It is another object of the present invention to provide a white balanceadjustment device which is capable of operating in a variety of modescorresponding to particular lighting contexts.

It is still another object of the present invention to provide a whitebalance adjustment device which is capable of accurately determining thetype of light source used to illuminate a photographic subject andperforming white balancing in accordance with such a determination.

It is yet a further object of the present invention to provide a whitebalance adjustment device which is particularly cable of determining thetype of fluorescent lighting used in fluorescent lighting contexts.

It is still yet another object of the present invention to provide awhite balance adjustment device which performs white balance adjustmentsof video signals in accordance with determinations of the type oflighting used to illuminate a subject.

These and other objects are achieved by the present invention in that awhite balance adjustment device adapted for use in fluorescent lightingcontexts is defined. The white balance adjustment device includes animaging unit for forming an image of a subject and for outputting thatimage. Moreover, the white balance adjustment device includes anadjustment mode selection unit for selecting a white balance adjustmentmode according to the kind of light source used to illuminate thesubject. Further, the device has a measurement unit for measuring coloraspects of the light source used to illuminate the subject and foroutputting a color value corresponding to the color aspects. Finally,the device includes a white balance adjustment unit for adjusting thewhite balance of the output of the imaging unit in accordance with theadjustment mode selected by the adjustment mode selection unit and inaccordance with the color value measured by the measurement unit.

Finally, the present invention provides a method for performing whitebalance adjustment based on the kind of light source used to illuminatea subject. The method includes the steps of imaging a subject to producea video signal representing an image of the subject, color separatingthe video signal into its primary light color components, measuring thecolor attributes of light used to illuminate the subject to produce acolor measurement value, matching the color measurement value with apredetermined parameter to produce a processing parameter whichcorresponds to the type of light used to illuminate the subject, andperforming white balance adjustment of the video signal using theprocessing parameter.

The present invention is described in further detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other objects and advantages of the presentinvention will become apparent and more readily appreciated from thefollowing description of the preferred embodiments, taken in conjunctionwith the accompanying drawings, of which:

FIG. 1 is a block diagram which depicts a typical white balanceadjustment device.

FIG. 2 is a block diagram which depicts the general structure of thepresent invention.

FIG. 3 is a block diagram which depicts a white balance adjustmentdevice according to a first embodiment of the present invention.

FIG. 4 is a flow chart which depicts a white balance adjustment actionwhich is carried out by a white balance adjustment device according to apreferred embodiment of the present invention.

FIG. 5 is a flow chart which depicts the gain setting process in afluorescent lamp manual mode according to a preferred embodiment of thepresent invention.

FIG. 6 is a block diagram which depicts a white balance adjustmentdevice according to a second embodiment of the present invention.

FIG. 7 is a block diagram which depicts a white balance adjustmentdevice according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A detailed description of the preferred embodiments is set forth belowreferring to the drawing figures briefly described above. Whereappropriate, like parts will be referred to with like referencenumerals.

Referring now to FIG. 2, therein depicted is a blocked diagram of thegeneral structure of the preferred embodiment of the present invention.In particular, a white balance adjustment unit 503 is shown to receiveinputs from an imaging unit 501, an adjustment mode selection unit 502,and an color measurement unit 504. Based on the inputs from theaforementioned imaging unit 501, the adjustment mode selection unit 502,and color measurement unit 504, the white balance adjustment unit 503 isable to perform accurate and efficient white balance adjustment.

Referring now to FIG. 3, therein depicted is a white balance adjustmentdevice according to a first embodiment of the present invention. Thewhite balance adjustment device depicted in FIG. 3 is adapted to be usedwith a video camera, but should not be so restricted. Imaging unit 103comprises elements which convert light into electrical signals, and isconstituted by circuits for sampling, at a predetermined rate, theoutput signals from imaging elements such as CCD or MOS devices and thelike solid-state imaging elements. Such imaging elements will beapparent to those skilled in the art. Light rays are received from aphotographic subject (not shown) via optical member 101 and stop member102, and respective R (red), G (green), and B (blue) signals are output.Variable amplifiers 104R and 104B amplify the R and B signals fromimaging unit 103 at a gain set by a control unit 110 and output them toa signal processor 105. Control unit 110 may be a microcomputer,microprocessor, custom central processing unit, or other well knowndedicated control circuitry which can carry out the functionalitydefined by the present invention. In the case where control unit 110 isa microcomputer, typical support circuitry would include, but would notbe limited to, a random access memory (RAM), a read only memory (ROM),and an input/output (I/O) handler. Moreover, the G output of the imagingunit 103 is passed directly to the signal processor 105 without passingthrough an amplifier circuit. Adjustment of gain, set-up level, gammaand knee, etc., is performed by the signal processor 105, and imagesignals are output to a recording unit 106.

A color measurement unit 130 receives light from the camerasurroundings, and analyzes it into a red component (Rb), a greencomponent (Gb), and a blue component (Bb). Color separation in thismanner will be apparent to those skilled in the art. Signal currents areoutput corresponding to the red component (Rb), green component (Gb) andblue component (Bb) via a diffusing plate 131 on a R light receivingelement 132R, a G light receiving element 132G, and a B light receivingelement 132B. A logarithmic compression circuit 133 logarithmicallycompresses the respective signal currents, and outputs log Rb, log Gband log Bb signals. Subtraction circuits 134 and 135 calculate log(Rb/Gb) and log (Bb/Gb) based on the outputs of the logarithmiccompression circuit 133, and an expansion circuit 136 calculates Rb/Gb,Bb/Gb by antilog conversion of the output of the logarithmic compressioncircuit 133. Moreover, a current/voltage converter circuit 137 convertsthe Rb/Gb and Bb/Gb signals into voltage signals, and an A/D converter109 converts the voltage signals into digital signals and outputs themto control circuit 110.

A control table 108A for use in auto white balance is a memory which inauto mode, along with processing the values Rb/Gb and Bb/Gb asparameters, stores the gain of the variable amplifier circuits 104R and104B. A control table 108M for use in manual white balance is a memorywhich stores the gain for fine weather, cloudy, and tungsten lightsources which is produced when white balance adjustment device is set ina manual mode. A control table 108K for use in fluorescent lamp whitebalance situations is a memory to store the gains for the kind offluorescent lamp used in situations wherein fluorescent lamp manual modeis selected.

A photometric unit 107 measures the brightness of the light receivedfrom the photographic subject and outputs a value corresponding theretoto control unit 110. Such photometric units will be apparent to thoseskilled in the art. A fluorescent lamp color discrimination unit 140discriminates among the different kinds of fluorescent lighting sources,based on the Rb/Gb color measurement result of color measurement unit130, and looks up the gain of the variable amplifier circuits 104R and104B corresponding to the kind of fluorescent lamp from the controltable 108K for fluorescent lamp white balance use.

The control unit 110 performs sequence control of the camera and variouscalculation processes. Additionally, control unit 110 performs whitebalance adjustment for the R, G and B output signals of the imaging unit103. Furthermore, the white balance adjustment switch 120 is a switchfor the selection of the adjustment mode. Switch 121 is a switch whichis used to select an auto white balance mode when such an operation isdesired from the white balance adjustment device. Switches 122-125 areswitches for the selection of the light source in a manual white balanceadjustment mode. In particular, switches 122-125 may be used to selectamong lighting states related to fine weather, cloudy weather,fluorescent lamp/lighting and tungsten lamp/lighting.

Referring generally to FIGS. 3, 6, and 7, the imaging units 103, 203,and 303, respectively, constitute an embodiment for an imaging means forforming an image of a subject and outputting the image. The whitebalance adjustment switches 120, 220, and 320, respectively, constitutean embodiment for an adjustment mode selection means for selecting awhite balance adjustment mode according to the kind of light source usedto illuminate the subject. Color measurement units 130, 230, and 330,respectively, constitute a color measurement means for measuring thecolor aspects of the light source used to illuminate the subject and foroutputting a color value corresponding to the color aspects. Finally,the control units 110, 210, and 310, the fluorescent lamp discriminationunits 140, 240, and 340, and the variable amplifier circuits 104R, 104B;204R, 204B; and 304R, 304B, respectively, constitute an embodiment for awhite balance adjustment means for adjusting the white balance of theoutput of the imaging means in accordance with the adjustment modeselected by the adjustment mode selection means and in accordance withthe color value measured by the color measurement means.

Referring now to FIGS. 4 and 5, therein depicted are flow charts whichillustrate the white balance adjustment actions which are carried out bya white balance adjustment device according to an embodiment of thepresent invention. In particular, the actions illustrated in FIG. 4 arecarried out by control unit 110. FIG. 5 depicts a flow chart whichillustrates the gain decision process of fluorescent lamp colordiscrimination circuit 140 in the fluorescent lamp manual mode. Theactions of the first preferred embodiment will be described withreference to these flow charts. It should be understood that while theactions depicted in the flow charts are preferably implemented usingcomputer software (e.g., via programs), such actions also may behard-wired.

First, in step S1 of FIG. 4, it is determined whether or not thephotographic button (not shown), has been half depressed; if it has beenhalf depressed, proceeding to step S2, the subject brightness ismeasured by means of photometric unit 107. Accordingly, the measurementof the brightness level by photometric unit 107, for example, allows thecontrol unit 110, for example, to add the brightness level to the whitebalance adjustment process in order to gain further accuracy in carryingout white balance adjustments of the video signal. At step S3, accordingto the adjustment mode selected by the white balance adjustment switch120, the program branches to one of steps S4-S8. Such branching can becarried out using typical branching structures like that of theC-language "switch" construct. Namely, when the "auto" mode has beenselected by means of switch 121, proceeding to step S4, the gaincorresponding to the Rb/Gb color measurement result is looked up fromthe control table 108A for auto white balance use. When "fine weather"of the manual mode has been selected by means of switch 122, proceedingto step S5, the gain corresponding to fine weather is read out from thecontrol table 108M for manual white balance use. Moreover, when "cloudy"of the manual mode has been selected by means of switch 123, proceedingto step S6, the gain corresponding to cloudy weather is read out fromthe control table 108M for manual white balance use. Furthermore, when"tungsten light" of the manual mode has been selected by means of switch125, proceeding to step S7, the gain corresponding to tungsten light isread out from the control table 108M for manual white balance use.

When the "fluorescent lamp" manual mode has been selected by means ofswitch 124, proceeding to step S8, the gain is next decided in thefluorescent lamp manual mode by means of the fluorescent lamp colordiscrimination unit 140. At step S21 of FIG. 5, the Rb/Gb colormeasurement result is read out from the color measurement unit 130. Atstep S22, it is determined whether Rb/Gb is greater than a previouslyset value K1. If Rb/Gb is greater than K1, the program proceeds to stepS23; if not, it proceeds to step S24. In step S23, it is determined thatthe light source is an electric bulb of the color fluorescent lampvariety, and the gain for electric bulb color is read out from thecontrol table 108K for fluorescent lamp white balance use.

When, at step S22, programmatic flow results in a negative state, it isdetermined at step S24 whether or not K2<Rb/Gb≦K1; if this logic resultsin an affirmative state, the program proceeds to step S25, and if not,the program proceeds to step S26. In step S25, if it is determined thatthe light source is a white fluorescent lamp, the gain for whitefluorescent lamps is read out from the control table 108K forfluorescent lamp white balance use.

When, at step S24, programmatic flow resulted in a negative state, it isdetermined at step S26 whether or not K3<Rb/Gb≦K2; if this isaffirmative, the program proceeds to step S27, and if not, the programproceeds to step S28. At step S27, it is determined that the lightsource is a daylight white color fluorescent lamp, and the gain for adaylight white color fluorescent lamp is read out from the control table108K for fluorescent lamp white balance use. Moreover, at step S28, itis determined that the light source is a daylight color fluorescentlamp, and the gain for a daylight color fluorescent lamp is read outfrom the control table 108K for fluorescent lamp white balance use.

Returning to FIG. 4 at step S9, the gain decided according to theselected adjustment mode is set in the variable gain amplifiers 104R and104B, and the program proceeds to step S10. During step S10, it isdetermined whether or not the photographic button has been fullydepressed; if the button has been fully depressed, the program proceedsto step S11, and if not, the program returns to step S1. In step S11,the optimum color balance adjustment is performed for the illuminatinglight source by means of the variable gain amplifier circuits 104R and104B. Moreover, the above-mentioned processing by means of signalprocessor 105 has been performed and the output signals are recorded inthe recording unit 106.

In the foregoing manner, when the fluorescent lamp light source has beenselected in the manual white balance mode, because the amplificationgain of the R and B output signals of the imaging unit has been decidedbased on the Rb/Gb color measurement result, and the white balanceadjustment has been performed, the optimum white balance adjustment willbe performed with the kind of fluorescent lamp being automaticallydetermined. Even if a photographic subject is illuminated by one ofvarious kinds of fluorescent lamp, photography is possible with anatural white balance.

In the above-mentioned preferred embodiment, the kind of fluorescentlamp/lighting source is determined by fluorescent discrimination unit140 based on the red component color measurement result Rb/Gb asillustrated in FIG. 5. The particular kind of fluorescent lamp/lightingsource may also be determined, as shown in FIG. 6, by the fluorescentlamp color discrimination unit 240 based on the blue component colormeasurement result Bb/Gb. Moreover, as shown in FIG. 7, the kind offluorescent lamp may also be determined by the fluorescent lamp colordiscrimination unit 340 based on the results of both the red componentRb/Gb and the blue component Bb/Gb. In any event, the present preferredembodiments according to the present invention provide for fluorescentlamp/lighting source detection selection freedom as proper white balanceadjustment will occur despite the fluorescent lighting source. Moreover,it will be apparent to those persons skilled in the art that a device ofthe type depicted in FIGS. 6 or 7, with the fluorescent lampdiscrimination units 240 or 340 eliminated, is similar to the whitebalance adjustment device depicted in FIG. 3. Accordingly, descriptionsof other preferred embodiments of devices depicted by FIGS. 6 and 7 areomitted.

By means of the present invention as described above, when theadjustment mode is selected according to the fluorescent lamp/lightsource, based on color temperature information of the light illuminatingthe subject, the white balance of the output of an imaging means isadjusted so that the kind of fluorescent lamp is automatically detectedand an optimum adjustment of the white balance is performed. As such,the present invention allows imaging with a natural white balancewhatever the kind of fluorescent lamp/light source that is used toilluminate the subject.

The present invention is not limited to the structure or operation ofthe preferred embodiments described above, and it goes without sayingthat many modifications and changes may be made to the form, structureand operation without departing from the spirit or principles of theinvention, the scope of which is defined in the appended claims andtheir equivalents.

What is claimed is:
 1. A white balance adjustment device adapted for use in fluorescent light source contexts, said white balance adjustment device comprising:imaging means for forming an image of a subject and for outputting said image; adjustment mode selection means for selecting a white balance adjustment mode according to the kind of light source used to illuminate said subject; measurement means for measuring color aspects of the light source used to illuminate said subject and for outputting a color value corresponding to said color aspects; a fluorescent lamp color discrimination unit to determine a type of fluorescent light source used to illuminate said subject; white balance adjustment means for adjusting the white balance of the output of said imaging means in accordance with the adjustment mode selected by said adjustment mode selection means and in accordance with the color value measured by said measurement means and the type of fluorescent light source used to illuminate said subject as determined by said fluorescent lamp color discrimination unit; and a photometric unit measuring the brightness of the light source used to illuminate said subject and outputting a corresponding photometric value.
 2. The white balance adjustment device according to claim 1, wherein said white balance adjustment means further adjusting the white balance of the output of said imaging means based on said photometric value.
 3. A method of white balance adjusting a video signal adapted for use in fluorescent light source contexts comprising:imaging a subject to produce said video signal representing an image of the subject; color separating said video signal into its primary light color components; measuring the color component attributes of light used to illuminate said subject to produce a color measurement value; determining a fluorescent light source type corresponding to a fluorescent light source used to illuminate said subject to produce a fluorescent light determination value; matching the color measurement value with a predetermined color parameter to produce a color processing parameter, said predetermined color parameter corresponding to the type of light used to illuminate the subject; matching the fluorescent light determination value with a predetermined fluorescent light parameter to produce a fluorescent light processing parameter, said predetermined fluorescent light parameter corresponding to the type of fluorescent light used to illuminate said subject; and performing white balance adjustment of the video signal using the fluorescent light processing parameter.
 4. A white balance adjustment device adapted for use in fluorescent light source contexts, comprising:an imaging unit imaging a subject and outputting a video signal; an adjustment mode selection unit to allow selection of a white balance adjustment mode according to a kind of light source used to illuminate said subject; a fluorescent lamp color discrimination unit to determine a type of fluorescent light source used to illuminate said subject; a white balance adjustment unit adjusting white balance characteristics of said video signal in accordance with said white balance adjustment mode selected by said adjustment mode selection unit and based on said type of fluorescent light source used to illuminate said subject as determined by said fluorescent lamp color discrimination unit; and a photometric unit measuring the brightness of the fluorescent light source used to illuminate said subject and outputting a corresponding photometric value.
 5. The white balance adjustment device according to claim 4, wherein said white balance adjustment unit further adjusting said white balance characteristics of said video signal based on said photometric value.
 6. A white balance adjustment unit adapted for use in fluorescent lighting contexts, comprising:an imaging unit imaging a subject and outputting a video signal having white balance characteristics; a fluorescent lamp color discrimination unit determining a type of fluorescent light source used to illuminate said subject and outputting a corresponding light source type value; a white balance adjustment unit adjusting said white balance characteristics of said video signal in accordance with said light source value output by said fluorescent lamp color discrimination unit; and a photometric unit measuring brightness of said subject as imaged by said imaging unit and outputting a corresponding brightness signal; wherein said white balance adjustment unit further adjusting said white balance characteristics of said video signal based on said brightness signal output by said photometric unit.
 7. A white balance adjustment device comprising:an imaging unit forming an image of a subject and outputting the image; an adjusting mode selection unit selecting a first whim balance adjusting mode which automatically adjusts the whim balance within a first range and a second white balance adjusting mode which automatically adjusts the white balance within a second range which is narrower than the first range; and a white balance adjustment unit adjusting the white balance of the output of said imaging unit in accordance with the adjusting mode selected by said adjustment mode selection unit.
 8. The white balance adjustment device according to claim 7, further comprising:a measurement unit for measuring color aspects of the light source used to illuminate the photographic subject and outputting a color value corresponding to the color aspects; and wherein the white balance adjustment unit adjusts the white balance in accordance with the color value measured by said measurement unit.
 9. A white balance adjustment device comprising:an imaging unit forming an image of a subject and outputting the image; a measurement unit measuring color aspects of the light source used to illuminate the subject and outputting a color value corresponding to the color aspects; an adjustment mode selection unit selecting a first white balance adjusting mode or a second white balance adjusting mode; white balance adjustment unit adjusting the white balance of the output of said imaging unit in accordance with the adjustment mode selected by said adjustment mode selection unit; and wherein the range of the color value covered by a set value of white balance in the second white balance adjustment mode is wider than in the first white balance adjusting mode.
 10. The white balance adjustment device according to claim 9, wherein the second white balance adjusting mode is used in a fluorescent lighting context which automatically adjusts the white balance in accordance with a plurality of kinds of fluorescent lights.
 11. The white balance adjustment device according to claim 10, wherein the plurality of kinds of fluorescent lights illuminate electric bulb color, white color daylight color, and daylight.
 12. A white balance adjustment device adapted for use in fluorescent light source contexts, said white balance adjustment device comprising:imaging means for forming an image of a subject and for outputting said image; adjustment mode selection means for selecting a white balance adjustment mode from a plurality of modes according to the kind of light source used to illuminate said subject, said plurality of modes including an auto mode which automatically adjusts the white balance in accordance with the kind of light source used to illuminate the subject and a manual mode which adjusts the white balance in accordance with the kind of light source indicated by a user and which includes the mode used in fluorescent lighting contexts which adjusts white balance automatically within a range that is proper for a plurality of fluorescent lighting contexts; measurement means for measuring color aspects of the light source used to illuminate said subject and for outputting a color value corresponding to said color aspects; and white balance adjustment means for adjusting the white balance of the output of said imaging means in accordance with the adjustment mode selected by said adjustment mode selection means and in accordance with the color value measured by said measurement means. 